Combined Risk Index Report for Solomon Islands
Combined Risk Index Explanation
The Combined Risk Index is calculated by normalizing the values of the following columns:
- Rainfall in driest quarter: Lower value indicates higher risk
- Height above sea level: Lower value indicates higher risk
- Height above drainage network: Lower value indicates higher risk
Each column is normalized to a range between 0 and 1, where 0 represents the lowest risk and 1 represents the highest risk. The Combined Risk Index is the average of these normalized values.
Note that for the normalization:
- Height above sea level values above 10m are set to 10m to account for low risk from tidal surge/tsunami/sea level rise beyond this height.
- Height above drainage network values above 10 are set to 10 to account for low risk this high above drainage networks.
- Rainfall in driest quarter values above 800 are set to 800 to account for more ability to rely on rainwater
In the Pacific context, these variables are crucial due to their direct impact on communities' vulnerability to natural disasters, accessibility, and overall resilience:
- Rainfall in driest quarter: Essential for understanding drought risks and scope for people to rely on rainwater harvesting.
- Height above sea level: Elevation is critical in assessing flood and storm surge risks. Lower elevations are more vulnerable.
- Height above drainage network: Directly measures the susceptibility to flooding events, a significant hazard in the Pacific.
High Risk Sites Classification
High risk sites are classified as follows:
- Rainfall in driest quarter: Sites with values below 400mm.
- Height above sea level: Sites with values below 5m above sea level.
- Height above drainage network: Sites with values below 5m above nearest drainage network.
The percentage of high-risk sites is calculated as the number of high-risk sites divided by the total number of sites.
Summary Table
| Province | Mean Rainfall in Driest Quarter (mm) | Median Rainfall in Driest Quarter (mm) | Std Dev Rainfall in Driest Quarter (mm) | Mean Height above Sea Level (m) | Median Height above Sea Level (m) | Std Dev Height above Sea Level (m) | Mean Height above Drainage Network (m) | Median Height above Drainage Network (m) | Std Dev Height above Drainage Network (m) | High Risk Sites (Rainfall) | High Risk Sites (Height above Sea Level) | High Risk Sites (Height above Drainage Network) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rennell and Bellona | 501 | 500 | 21 | 18 | 13 | 19 | 6 | 5 | 5 | 18 (100%) | 6 (33%) | 16 (88%) |
| Temotu | 978 | 972 | 16 | 13 | 11 | 15 | 10 | 8 | 8 | 0 (0%) | 24 (44%) | 30 (55%) |
| Western | 726 | 734 | 69 | 15 | 10 | 17 | 13 | 10 | 16 | 114 (73%) | 73 (47%) | 77 (49%) |
| Malaita | 638 | 640 | 23 | 62 | 14 | 126 | 28 | 9 | 50 | 301 (87%) | 121 (35%) | 173 (50%) |
| Makira-Ulawa | 709 | 718 | 43 | 17 | 11 | 23 | 13 | 8 | 18 | 108 (90%) | 53 (44%) | 71 (59%) |
| Guadalcanal | 358 | 340 | 58 | 36 | 12 | 73 | 14 | 7 | 29 | 165 (98%) | 70 (41%) | 100 (59%) |
| Isabel | 538 | 525 | 45 | 35 | 11 | 91 | 18 | 7 | 40 | 102 (99%) | 46 (44%) | 64 (62%) |
| Honiara | 289 | 288 | 2 | 23 | 18 | 18 | 12 | 11 | 10 | 47 (100%) | 11 (23%) | 22 (46%) |
| Choiseul | 734 | 738 | 28 | 9 | 7 | 9 | 8 | 6 | 8 | 85 (91%) | 62 (66%) | 67 (72%) |
| Central | 347 | 347 | 1 | 10 | 7 | 9 | 10 | 7 | 9 | 3 (100%) | 2 (66%) | 2 (66%) |
| National | 595 | 635 | 159 | 35 | 12 | 84 | 18 | 8 | 35 | 943 (85%) | 468 (42%) | 622 (56%) |
Charts
Mean Rainfall in Driest Quarter by Province
Mean Height above Sea Level by Province
Mean Height above Drainage Network by Province
